Simultaneous degradation and reduction of multiple organic compounds by poly(vinyl imidazole) cryogel-templated Co, Ni, and Cu metal nanoparticles

Abstract

Superporous poly(vinyl imidazole) (p(VI)) cryogel was employed to prepare Co, Ni and Cu metal nanoparticles in situ. The catalytic performance of p(VI)–M cryogel composites in the degradation of methylene blue (MB) and eosin yellow (EY) and in 4-nitrophenol (4-NP) reduction in the presence of NaBH₄ in aqueous media was determined as Co > Cu > Ni for MB, Co > Ni > Cu for EY and Ni ≈ Co > Cu for 4-NP. Binary and tertiary mixtures of these substrates (dyes and 4-NP) were also used to assess the best catalytic performance among the p(VI)–M composites, showing that p(VI)–Co was the best catalyst with over 95% conversion in 5 min regardless of single, binary or tertiary substrate mixtures. It was further shown that over 99% conversion for each substrate in the MB + EY + 4-NP triple mixture can be readily attained within ∼30 min of reaction time. P(VI)–Co composite catalysts are capable of simultaneous elimination of multiple toxic organic compounds from aqueous environments, providing great opportunities in real applications.